Silent switches



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SILENT SWITCHES Filed Feb, 12, 1958 2 Sheets-Sheet. 2

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a3 al United States Patentl 'TO 2,987,592 SILENT SWITCHES Chester W. Johnson, Norwell, Mass. (Box 303, Rockland, Mass.), assignor of one-half to Allan Q. Mowatt, Lexington, Mass.

Filed Feb. 12, 1958, Ser. No. 714,826 111 Claims. (Cl. 200-67) This invention relates to switches for controlling electric circuits, and particularly to wall switches of the socalled toggle type used in homes and olces for controlling lighting circuits, such as exemplified in my prior Patents No. 2,738,389, dated March 13, 1956, and No. 2,737,557, dated March 6, 1956.

' The main object of the present invention is to provide a switch of this type which will be practically noiseless in operation. Further objects are to provide a switch of this type having capacity for easily and cheaply modifying its operating characteristics to suit various uses, such as providing for either slow make with quick break or quick make and break of the circuit, and to avoid the faults of stopping of the parts in intermediate position between the oi and on extremes Iof their movement, with intermittent or trembling contact in the on position with resultant arcing constituting a tire hazard, and-of reverse creep of the parts out of their intended on or off position. Other objects of the invention include the provision of a simple structure which can be easily and rapidly assembled out of inexpensive components of wide availability to make a switch having long life and freedom from failure in action.

A novel feature of the present invention is the use of a yielding fulcrum on which a yielding contact-making element is supported for rocking or tilting movement into and out of engagement with its cooperating operatively fixed contact element, to make or break the electrical circuit through the switch. The manually-operated actuator or thumb-lever remains always in engagement'with the movable contact-maker with the avoidance of any snap or slap `at this point, while the weight of the single moving contact-maker, of thin spring stock, is so light that the closing of the switch makes no clearly audible sound. Further, in breakingl the circuit the contactmaker in the two-way or single contact switch strikes nothing and hence the switch is soundless in this opera- Ition also, though breaking the circuit quickly with the avoidance' of the formation of an arc.

Additionally, the novel construction admits of conversion to a three-way switch by merely the addition of a simple fixed part carrying another contact and the addition of a further contact on the moving contact-maker for engagement therewith.

A further feature of the invention is the provision of a novel form of actuating element adapted for manipulation either by the fingers of the hand or by a rubbing or stroking contact with the palm or back of the hand, the elbow, or the forearm of the user.

Other objects of the invention, and the manner of attainment of these and those already indicated, are set forth hereinafter.

Illustrative embodiments of the invention are shown Patented June 6,. 1961 dotted lines, with the yielding fulcrum element of FIGS. 1 to 3.

FIGS. 5 and 6 are plan and front elevation of the novel contact-maker.

FIG. 7 is a plan view of the switch casing of FIGS. 1 and 2, with all parts removed except the xed contact element and the perch on which the contact-maker is mounted, showing the provision for attaching the line wires.

FIG.l 8 is a left-hand elevation of the xed contact element of FIG. 7.

FIG. 9 is a plan view corresponding to FIG. 7, with the contact-maker of FIGS. 5 and 6, the yielding fulcrum of FIG. 4, and a form of thumb-lever actuating spring alternative to that of FIGS. 2 and 3.

v FIG. 10 is a side elevation, broken away, of the cornplete switch of FIG. 9, with its cover and wall plate in place.

f FIG. 1l shows the yielding fulcrum of FIGS. 4, 7 and 10 in elevation in place within the casing.

FIG. 12 is a front elevation of the thumb-lever actuating spring of FIGS. 9 and 10 in place in the bottom of the casing.

The casing 1 is identicalV in all the forms shown, cornprising a molded plastic box With lugs 3 receiving the screws 5 holding the cover 7 thereon, the cover having the usual slots 9 for the screws which fasten the switch in place in the switch box. The casing is formed with a concave-edged slot 11 in one wall and two concaveedged slots 13, 15, in the other wall, extending down nearly to the bottom of the box. In the slot 15 is fitted with a snug sliding tit the fixed contact shown in FIG. 8, the vertical portion 17 being equipped with a binding screw 19 and having rounded vertical edges conforming to the curved margins of the slot 15. A horizontal integral extension 21 of this element, which is preferably made of brass or other good electrically-conducting metal, has a contact 23, preferably of silver, riveted therein with its working end downward. A cut 25 in one edge of portion 21 gives clearance for the thumb-lever, to be described; The element 17 fills only the lower half of slot 15, the upper half being occupied by a strip of plastic 27 having its top ilush with the top edge of the casing 1.

Slot 11 is occupied throughout its lower half by an element similar to 17 equipped with a binding screw` 29 and having a short horizontal inward extension 31 of the component metal provided with a hole 33 for the rivet 35 4which mounts the narrow blade 37 of the contact-maker 39, best shown in FIGS. 5 and 6, in place on the element 31.' The upper half of slot 11 is likewise occupied by a close-titting strip of plastic 41, terminating iiush with the upper edge of the casing 1.

vThe third slot 13 is provided for the insertion of a third element similar to 21, FIG. 8, when the switch is to be made as a 3-way switch. Otherwise, it is filled with a strip of plastic 43 as indicated in FIG. l.

The contact-maker 39 is made of electrically-conductive spring stock, preferably of phosphor bronze sheet. It is forked or split throughout the main portion of its length being U-shaped in plan view, with its legs integral and disposed edgewise to eachother, the part 37 whereby it is mounted on terminal 31 being bent upward at its lefthand end and then into a plane parallel with the longer portion of part 37, as shown in Fig. 6. The connecting portion 46 of the part 45 of this element as well as the free end of part 45 lie in this plane, while the midlength portion 47V is depressed-in an arc of generally elliptical profile. The curve is carried slightly beyond the axis of the ellipse to form over-hanging shoulders 49. A silver contact point 51 is riveted to the free end of part 45, to engage ,theY contact point 23 on the terminal 17, when the switch is closed, as shown in FIG. 10.

The bottom surface of the arcuate portion 47 of the free part 45 of contact-maker 39 is continuously engaged at one location only by a transverse ridge 53, FIGS. 2, 4 7, 10 and ll., of a spring-blade 55 held by contact of its downturned ends 57 with the end walls and bottom of the casing 1, these ends being conned between lugs 59 formed on the bottom of the casing.

Thumb-lever 61, composed of non-conducting material, preferably plastic, has an integral extension 63 with rounded end which stands within the curve ofthe depressed arcuate portion or concavity 47 of contact-maker 39, and remains ever in contact therewith through the resilience of the leg 37 of the contact-maker combined with the upward thrust of the ridge 53 of spn'ngblade 55. The thumb-lever rocks on its integral trunnions 65 which are received in seats 67 formed in the opposite side walls of casing 1, being held therein by the overlying cover 7.

When the thumb-lever is rocked clockwise into the position shown in FIGS. 1 and 2 and in full linesY in FIG. 4, the extension 63 or actuator rides along the left-hand Y portion of the arc 47, rocking the free part 39 onthe fulcrum 53, with exing of part 37, depressing the end 46 and causing the free end of part 45 to rise and bring contact 51 thereon into engagement with xed contact 23 on terminal portion 21, thus closing the circuit between the latter and the other terminal 31 on which contact 21V is xed in conducting relation.

When the thumb-lever 61 is moved counterclockwise Y in FIGS. l, 2 and into the dotted-line position of FIG. 4, the actuator 63 moves along the interior surface off the are 47 in continuous contact therewith, depressing the ridge 53, the yielding `fulcrum, as it passes over it. It then proceeds upward along the right-hand half of arc 47. As soon as the actuatorV 63 has passed the ridge 53, the combined resilience of spring-blade 55 pushing upward through the ridge 53 on the bottom of a'rc 47 and the inherent resilience of the part 37 of contact-maker 39, coupled with the downward component of thrust exerted on the arc by actuator 63, cause the contactmaker to tilt into the dotted line position and the free end 45 of the contact-maker to fly downward with a quick motion which separates the two contacts 23 and 51 too fast to allow an electric arc to be formed as the circuit is thus broken. Y l

Thus it will be apparent that the tilting or see-saw movement of the contact-maker 39 is accelerated in both directions of movement of its contact 51 through the use of a yielding fulcrum, the ridge 53, which resiliently presses upward on the arcuate part 47 of the contact-maker and moves upward as the actuator 63 passesY theridge- 53, creating unbalanced forces, effective downward at the actuator and upward at the fulcrumV or ridge. These unbalanced forces constitute a turning couple Vwhich gives a Ifast and wide throw to the free end 45 of contactmaker blade 39 for asmall angular movement ofthe thumb-lever, becauseY of the great difference-"inl lengthY between the short power arm and the long work arm o f the lever comprised by the free portion 39 rocking'on ridge53. Y o "o During the rising or circuit-closing movement of the part 39, the relation changesrfrom a' lever ofithe second orderrto a lever of the tlirst order, andA in thereverse or circuit-breaking Vmovement the lever changes backv from the rst to the second order.

nothing at all, and hence Ygives rise to noaudible sound;Y

The thumb-lever 61 is preferably urged into and heldin its extreme angular position in both directions by aspring 71 which in the form of FIGS. 2 and 3,.'is more or lessf the v'shape of a safety pin.i The left-.handfeud oiftlle` long and straight bottom portion of Vthis spring is received in a notch 73 formed in one of the lugs 59 on the bottom of casing 1, while the coil lits into a pocket 75 provided in another lug 77 also formed on the bottom of the casing. This pocket 75 holds the spring upright, so that its shorter humped and downwardly curved portion engages within a V-shaped notch 79 in a-projection 81 on the bottom end of Vthumb-lever 61-...1Thefpart 81 may be a lateral extension of the actuator 63. As the thumb-lever is rocked in either direction, the projection 81 rides over the crest of the curve of this shorter portion of spring 71, whereupon the slope of the curve cams the portion 81 laterally and carries the thumb-lever onward to the limit of its travel in the direction in which it is Vbeing impelled by the users hand. Preferably the high pointV of the curve of this portion of the spring is located slightly to the left of the vertical plane through the thumb-levers Vpivots 65, so as to give a slightly slower closing of the switch and a slightly faster opening *of the switch when the thumb-lever is rocked, for the sake of silence. o

The switch cannot jar into oi position, because once the projection 81 is over the high point of the spring, the latters upward push holds the thumb-lever in the on-position. But the thumb-lever moves reversely to open the circuit ata mere touch.

In FIGS. 9 and I0 a spring 83 of dierentshape as more clearly illustrated in FIG. 12 is used. Its ends turn down at right angles to its length and are received respectively in notches 73 and 85 of lugs 59 whereby it is held disposed in a vertical plane. At approximate midlength it has an upward bend 87 engaging within the. notch 79 of downward extension 81 on the thumb-lever, which hump works in analogous manner to spring 71 to continue the travel of thumb-lever 61 to its extreme position as soon as the thumb-lever is pushed past the vertical plane extending through its pivots. The spring arches over lug 77, so that either type of spring as preferred may be used in the same casing.

The safety pin type of spring 71 with its oiset high point, as noted, gives a slow make and a quick break of the circuit. The hump spring 87 gives a quick make and a quick break also, when coordinated with proper shaping and positioning of the arcuate depression 47 of the contact-maker. That is, by shortening the radius of the arc in the blade 39 of the contact-maker and lengthening this blade, a very quick make 'and quick break can be attained, through the difference in the radii of the arc and of the thumb-lever. Such change shortens` the arc Vof movement of the thumb-lever, with attendant multiplication of the throw of the contact-bearing end of part.39. A valuable featurev of the novel construction is thatthe Y switch will operate with omission of either type of thumb- The yielding ulcrum alone thus provides the force needed tol Ysecure firm engagement of the contacts in these-cases; As is obvious,V the sharper the angle of the fulcrum 53 the. quicker themake and break. i

The yielding fulcrum provided by the ridge 53 on fulcrum-blade 55l thus makes it easily possible to modify the operating'characteristics and capabilities of the switch'. It further makes it very easy to get correcttting ofthe component parts in assembling the switch. It veliminates the need for the critical dimensions which aref needed in order to make the actuator 63 pass smoothly over the fulcrum when this fulcrum is'unyielding, as 'for'- instance in the form of a ridge on the casing bottom, and also compensates for any wear of the actuator 63 on the thumblever. Also, as noted, it permits changes of the radinsy of the. actuator'and ofthe shape ofthe arc 47 incident to increasing the speed of make and break.

The usualtype ofleverwithprojecting handles isused; if*V preferred, the.handleY may. be-cut. ot flush with the body at the dotted line 62, FIG. 2, enabling the thumblever to be rocked by pushing above or below center to put the switch on or off, or it can be rolled up or down with the ngers, palm, or forearm, the two ends of its at exposed face being ribbed or ridged to effect nonslip engagement with its protruding high end.

It is to be noted that the overhanging-shoulders 49 of the arcuate portion 47 of the free portion 45 of resilient contact-maker 39 engage the actuator 63 and serve as impositive and yielding stops to stop the throw of the thumb-lever silently and limit its range of movement. If the attempt is made to force the thumb-lever beyond the stopping points thus created, the cam 89 formed integrally on one side of thumb-lever 61 engages with the under side of switch-cover 7 to check further angular movement of the thumb-lever and spare the working parts from injury or disarrangement.

Conversion of the switch to 3-way operation is effected by merely fixing a third contact 91, FIGS. 4, 5 and 6, on the part 46 of contact-maker 39, replacing the plastic blank 43, FIGS. 1, 7 and 9, with a second terminal element 21, FIG. 8, located in the bottom of the slot 13, and filling the upper half of the slot with a half-length blank of plastic material like 41. As is obvious, the additional contact 91 engages the contact 23 on the added terminal piece 21.

An economically important feature of the novel construction is the ease and rapidity with which the switch is assembled. In doing so, fulcrum spring-blade 55 is simply dropped into place between the lugs 59, the thumblever spring 71 or 83, if either is used, is lowered into its notches 73, 75, or 85 by a pair of thin-nosed pliers, the terminal piece 31 with contact-maker 39 already riveted thereto is slipped into slot 11, the other terminal 21 is slipped into slot 15, the thumb-lever 61 dropped into seats 67, its actuator 63 taking its place within the arc 47 and the fork 79 astride the thumb-lever spring 71 or 83, and the switch cover 7 applied and screwed down. 'Ihe assembly time and consequent labor cost are thus made very moderate, no tting or adjustment or complex manipulation being required.

While I have illustrated and described certain forms in which the invention may be embodied, I am aware that many modications may be made therein by any person skilled in the art, without departing from the scope of the invention as expressed in the claims. Therefore, I do not wish to be limited to the particular forms shown, or to the details of construction thereof, but what I do claim is:

1. An electric switch having in combination a fixed contact, a one-piece contact-maker of resilient sheet metal in U-shape with its legs in edgewise relation to each other, having the end of one leg xed, an actuator tilting the contact-maker successively in opposite directions, a yielding fulcrum on which the contact-maker tilts, and a contact on the free end of the other leg of the contactmaker engaging the xed contact in one direction of the contact-makers movement and disengaged from the iixed contact in the other direction of the contact-makers movement, the contact-maker having an arcuate portion providing shoulders forming impositive and yielding stops engaging and arresting the actuator and limiting the latters range of movement.

2. An electric switch having in combination a xed contact, a moving contact, a pivoted actuator, a spring urging the actuator to tilt into its extreme angular position in both directions, a resilient contact-maker having one end rfixed and carrying the moving contact on its free other end and rocked by the actuator and having impositive and yielding stop means thereon limiting the movement of the actuator, and a yielding fulcrum on which the contact-maker rocks.

3. An electric switch having in combination a xed contact, a contact maker of resilient conducting material having two arms integrally joined and extending side by side, `a perch'on whichone Yarm is fixed, a contact in operatively xed relation on the free end of the free a'rnr, a manually operated actuator engaging the free arm-'at different points in the latters length as the actuator is moved, a yielding fulcrum engaging the free arm intermediate the range of movement of the actuator along the -free arm and urging the latter toward the actuator and tilting the free arm as the actuator passes the fulcrum and bringing the two contacts into engagement, and tilting the free arm reversely as the actuator passes the fulcrum in the reverse direction, thus separating the two contacts, and means impelling the actuator in its direction of, manual movement more strongly when moving to separate the contact than when moving to bring the contacts into engagement with each other. l

4. An electric switch having in combination a switch casing, an actuator pivoted therein, a one-piece sprn'g blade split longitudinally throughout the greater portion of its length and with its legs laterally offset and in edgewise relation to each other, mounted in the casing by one of its free ends, a contact on the other `free end of the blade, a fulcrum engaged by the portion of the blade having the contact and on which such portion is rocked by engagement with the actuator, and a second contact engaged by the contact on the blade as the said portion of the blade is rocked.

5. An electric switch having in combination a tixed contact, a contact-maker formed of resilient sheet metal and having an arcuate portion, a pivoted manually operable actuator in sliding contact with the concave surface of the arcuate portion to rock the contact-maker and limited in its movement by the arcuate portion, a spring urging the actuator to tilt into its extreme angular position in both directions, a yielding fulcrum engaging the convex sur-face of the arcuate portion, and a contact on the contact-maker engaging the fixed contact when the contact-maker is rocked in one direction.

6. An electric switch having in combination a casing, a thumb-lever pivoted therein, a contact-maker, means resiliently pressing the contact-maker against a portion of the thumb-lever and engaging the contact-maker at only one location in the latters length, and a spring acting on the thumb-lever to continue the latters movement as the portion thereof engaged by the contact-maker passes the plane through the pivotal axis of the thumb-lever and the said location.

7. An electric switch having in combination a casing, contact-making means therein, a cover, and a thumb-lever for operating such means, pivoted in the casing and having a portion protruding from the casing through the cover, such portion having its outermost surface extending transversely with respect to the pivotal axis of the thumb-lever in a smooth convex curve for substantially the full extent of the thumb-lever in such direction.

8. An electric switch having in combination a iixed contact, a moving contact, a contact-maker of at resilient metal stock xedly mounted by one of its ends and carrying the moving contact on its free other end, an actuator to rock the contact-maker, a spring impelling the actuator, and a yielding fulcrum on which the contactmaker rocks, the contact-maker limiting and arresting the movement of the actuator.

9. An electric switch having in combination a casing, a fixed contact, a moving contact, a resilient contact-maker of Hat spring stock having the moving contact xed on its free end and having its other end xed on the casing, the contact-maker having an arcuate depression between the moving contact and the fixed end, a yielding fulcrum engaging the contact-maker within the length of the arcuate depression, an actuator pivoted in the casing and engaging the contact-maker within the arcuate depression to rock the contact-maker and arrested at the ends of the pivotal movements by engagement with the ends of the arcuate depression in the resilient contact-maker, and a spring impelling the actuator in its pivotal movements.

a fixed contact therein, a moving contact, a one-piece contact-maker of flat resilient metal having one end zterl in the casing and Vthe'other end free andc-with the moving contact lmounted on such `free end, an actuator pivotally mountedin the casing and slidably engaging the contactn lakerl between the xed end and the location of the moving Ycontact thereon, 4and a yielding fulcrum engaging the contact-maker within the scope of movement of the actuator along the contact-maker, the contact-maker being bent to form a concavity arresting the movement of the actuator at both ends of the 'latters travel.

11. An electric switch having in combination a contact-maker formed of lresilient Vsheet metal in integral U-shape with the legs of the U disposed edgewise to each other, means iixedly supporting the free end of one leg,

va Yfixed contact, a moving contact o n thev free end of the 8 other les, an actuato; to ro ckthe contact-maker .and a yielding on .which the contact-bearing leg rocks andgiengagingsolely with-the latter leg of the contactmak91`- "i-'xf Y .'V References vCited in the le` of this patent Y UNlIED STATES PATENTS v1,215,807 Hutt Feb. 1s, 1917 1,619,148 Miller r Mar. 1, 1921 ,1,878,667y `130th ..4 ,.V. V Sept. 20, 1932 1,912,623 `Douglas June 6, 1933 2,848,574 Hutt Aug. 19, 1958 `2,878,346 Y Andrews Mar. 17, 1959 Y .FOREIGN PATENTS 741,924 Great Britain ..-.1 Dec. 14,' 1955 

